112 lines
2.9 KiB
C
112 lines
2.9 KiB
C
/*
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* CDDL HEADER START
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*
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* This file and its contents are supplied under the terms of the
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* Common Development and Distribution License ("CDDL"), version 1.0.
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* You may only use this file in accordance with the terms of version
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* 1.0 of the CDDL.
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*
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* A full copy of the text of the CDDL should have accompanied this
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* source. A copy of the CDDL is also available via the Internet at
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* http://www.illumos.org/license/CDDL.
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2014 by Delphix. All rights reserved.
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*/
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#include <sys/bqueue.h>
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#include <sys/zfs_context.h>
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static inline bqueue_node_t *
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obj2node(bqueue_t *q, void *data)
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{
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return ((bqueue_node_t *)((char *)data + q->bq_node_offset));
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}
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/*
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* Initialize a blocking queue The maximum capacity of the queue is set to
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* size. Types that want to be stored in a bqueue must contain a bqueue_node_t,
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* and offset should give its offset from the start of the struct. Return 0 on
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* success, or -1 on failure.
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*/
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int
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bqueue_init(bqueue_t *q, uint64_t size, size_t node_offset)
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{
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list_create(&q->bq_list, node_offset + sizeof (bqueue_node_t),
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node_offset + offsetof(bqueue_node_t, bqn_node));
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cv_init(&q->bq_add_cv, NULL, CV_DEFAULT, NULL);
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cv_init(&q->bq_pop_cv, NULL, CV_DEFAULT, NULL);
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mutex_init(&q->bq_lock, NULL, MUTEX_DEFAULT, NULL);
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q->bq_node_offset = node_offset;
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q->bq_size = 0;
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q->bq_maxsize = size;
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return (0);
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}
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/*
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* Destroy a blocking queue. This function asserts that there are no
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* elements in the queue, and no one is blocked on the condition
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* variables.
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*/
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void
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bqueue_destroy(bqueue_t *q)
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{
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ASSERT0(q->bq_size);
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cv_destroy(&q->bq_add_cv);
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cv_destroy(&q->bq_pop_cv);
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mutex_destroy(&q->bq_lock);
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list_destroy(&q->bq_list);
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}
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/*
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* Add data to q, consuming size units of capacity. If there is insufficient
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* capacity to consume size units, block until capacity exists. Asserts size is
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* > 0.
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*/
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void
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bqueue_enqueue(bqueue_t *q, void *data, uint64_t item_size)
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{
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ASSERT3U(item_size, >, 0);
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ASSERT3U(item_size, <=, q->bq_maxsize);
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mutex_enter(&q->bq_lock);
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obj2node(q, data)->bqn_size = item_size;
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while (q->bq_size + item_size > q->bq_maxsize) {
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cv_wait_sig(&q->bq_add_cv, &q->bq_lock);
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}
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q->bq_size += item_size;
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list_insert_tail(&q->bq_list, data);
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cv_signal(&q->bq_pop_cv);
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mutex_exit(&q->bq_lock);
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}
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/*
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* Take the first element off of q. If there are no elements on the queue, wait
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* until one is put there. Return the removed element.
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*/
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void *
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bqueue_dequeue(bqueue_t *q)
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{
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void *ret = NULL;
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uint64_t item_size;
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mutex_enter(&q->bq_lock);
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while (q->bq_size == 0) {
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cv_wait_sig(&q->bq_pop_cv, &q->bq_lock);
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}
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ret = list_remove_head(&q->bq_list);
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ASSERT3P(ret, !=, NULL);
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item_size = obj2node(q, ret)->bqn_size;
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q->bq_size -= item_size;
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cv_signal(&q->bq_add_cv);
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mutex_exit(&q->bq_lock);
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return (ret);
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}
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/*
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* Returns true if the space used is 0.
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*/
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boolean_t
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bqueue_empty(bqueue_t *q)
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{
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return (q->bq_size == 0);
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}
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